The 'single' impulse responses were generated using a square room model made of only one material, except that the room size is 5*5cm.
The result is not a reverb, but a special EQ.

The 'double' impulse responses correspond to two single impulse responses in a row. It's like playing the signal in a 5 cm box, recording it, and then playing it again in the same box. Those 'double' impulse responses are much more colored than the 'single' ones.

Those impulse responses are really useful when it comes to 'color' a given sound. Especially handy to 'differentiate' a track inside a mix. Mono to stereo.

Single Bright Walls
Single Carpet On Pad
Single Cement
Single Ceramic Tiles
Single Concrete Painted
Single Concrete Unpainted
Single Drapery Light
Single Glass Window
Single Gypsum Board
Single Highs Dumper
Single Marble
Single Metal
Single Plaster On Lath
Single Plaster
Single Plywood Paneling
Single Studio Material
Single Varnished Wood
Single Warm Walls
Single Wood

Ampeg is a bass amp emulator, based on the Amplitube technology.
It includes an "Ambience" function, that's simple, efficient, and would deserve to be used on its own. Here it is, to be used in convolution reverbs.

A reverb map of a bedroom in a small Parisian flat. 64 IRs were recorded from 16 different spots in the room. As shown on the maps above that represent Reverb Time and Spectral Centroid for each IR, reverb variations between the different spots are important. The influence of the corridor on the bedroom is particularly visible.

Amongst other things, this shows that the notion of "reverb of a room" is not particularly well-defined. There is not ONE reverb for a given room. And this is a 10 sq. meter room, imagine the result with a bigger space.

Eight original 24bit mono -> mono impulse rsponses, from which are made mono->stereo Eight original 24bit mono -> mono impulse responses, from which are made mono->stereo and stereo-> stereo responses.

The "light" package is the spectrum almost as computed.
Files in the "dense" package have been compressed, giving a much denser kind of reverb.
Both are roughly 3s impulse responses.

From a perceptive point of view, those mono to stereo impulse responses are a variable mix of echoes and diffuse field.
The diffuse field is not unlike certain untreated medium sized rooms.
It also sounds a bit like the laboratory white noise based impulse responses one can find above.

Those special impulse responses are synthetised using the Lorenz chaotic oscillator.

Here are the sonograms of some of those impulse responses. It gives a good idea of what kind they are - click on the thumbnail to get the whole image :

We take the oscillator's spectrum as a sound file. This sound file will taken as a base for the impulse response. Here is how the spectrum - and the impulse response, behaves during the doubling period cascade :

period 2

period 4

...

period 16

period 32

...

period ∞

(simple echo)

(triple echo)

(15 echos)

(31 echos)

(diffuse field)

... so we have a transition from discrete echoes to diffuse field.

* How it was done :

1. logistic equation
2. spectrum (FFT)
3. real part of the spectrum will be left, imaginary part will be right
4. the spectrum is compressed (non real time), so the harmonics / echoes are more easily heard
5. export to audio files
6. the audio files are faded out, so it doesn't sound like a gated reverb, but like a "real" one
7. optimization (left/right perceptual balance, etc.)

A moderately chaotic behaviour around particular values of the system's parameters results in the rich and diverse ambiences featured in this set.

Most of these ambiences are "directional". This term refers to the fact that the sound clearly gives the impression of going from one channel / ear to another. In actual acoustic spaces, this can happen if one part of the room is mostly reflective or diffusing, and another part of the room mostly damped. For instance, LEDE control rooms are directional.

This is NOT the acoustic impulse response of the instrument (that could be obtained by playing a sweep at one end of the instrument for instance).
Instead, the response is derived from the instrument's spectrum.

The result is a mix of delays / diffuse field, which sound is not without connections with the original instrument's timbre.

- started from a mono instrument sample
- got the spectrum (FFT) ; this spectrum has two parts, real and imaginary
- real part is the left channel, imaginary the right channel
- compressed each channel to get a denser response (non real time compression)
- this response consists in a noisy echo, very long ; it has to be shorter for aesthetic reasons
- so, divided the spectrum into several parts ; the closer to the beginning, the more echo-like ; the closer to the end, the more diffuse.
- optimized (L/R balance, normalizing...)

The trombone spectrum being what it is, those impulse responses are very rich in noisy high frequencies.
It may be useful to soften them using the convolution engine's integrated EQs.

Speaker Echoes (v2)

Speakers in speakers in speakers in speakersin speakers in .....

Three set of speakers, three sets of echoes : a 1 way (generic), a 2 way (Infinity) and a 3 way (Sony). The first echo is reinjected into the same speaker for the second echo, and so on. Two variants for each case : echoes based on the actual IR / echoes based on the IR made symmetrical (sounds smoother).

Here the impulse responses are not supposed to resemble anything realistic : they are just designed to generate unexpected and hopefully interesting sounds.
Most of those reverbs have been used on this live show, actually on the main vocals.

Nine impulse responses, divided into three categories.
All impulse responses mono to stereo.

Specific sound design use, not suited for general purpose as a standard reverb !!Adds resonance and grain to static sounds, particularly suited to spacey keyboard pads.

There is a [mono -> mono] version and a [mono -> stereo] version.

The [mono -> stereo] uses the same base impulse responses for the left and right channels, with a 20ms delay and level compensing (-1.5dB on the non delayed channel).

* What it is

The impulse responses actually consist in a series of Dirac impulses, in a mostly random way but with elements of periodicity.
The overall envelope is of the damped kind.

Overall waveform view

Close waveform view

* Tips

* This is the raw impulse response. As such, it sounds a bit dirty and with a lot of high frequencies. For best results, use in conjunction with either the convolution engine's integrated EQs or an external EQ, to smooth the Diracs out. (use the EQ as you would with the usual lo pass EQs that are always to be found in non-convolution reverbs)